Abstract: Objective To establish a method for simultaneous determination of arsenic,mercury and selenium in water by graphite digestion and three channel atomic fluorescence spectrometry. Methods K₂Cr₂O₇-HNO₃-HClO₄ was used as the digestion solution,and the water sample was digested by graphite digester. Arsenic,mercury and selenium were simultaneously determined in water by three-channel atomic fluorescence method,quantified by standard curve method and the results were compared with the national standard method. Results In this method,arsenic and selenium were in the range of 1.0-20.0 μg/L,mercury was in the range of 0.10-2.00 μg/L,the correlation coefficients of standard curve were all greater than 0.999 0. The detection limits were 0.064 μg/L for arsenic,0.030 g/L for mercury and 0.051 μg/L for selenium. The relative standard deviations were 2.95% for arsenic,1.13% for mercury,and 1.34% for selenium. The relative deviations between the mean value of quality control samples and the standard value were 3.37% for arsenic,2.93% for mercury,and -3.39% for selenium. The average recoveries in the spiking experiment were 97.3% for arsenic,99.9% for mercury,and 103.3% for selenium. Paired t-test was used to compare the sample determination results of the two methods,and there was no statistical significance（all P>0.05）. Conclusions The method can improve the working efficiency and reduce the amount of chemical reagents. The curve linearity,detection limit,precision,accuracy and sample determination results of the method all meet the requirements of the national standard method,and having certain practical value.

Key words: Arsenic, mercury and selenium, Simultaneous determination, Atomic fluorescence, Graphite digestion, Water quality